This invention relates generally to internal combustion engines, and, more specifically, to an improved system for injecting heated and partially vaporized fuel into a conditioned airstream for forming a highly efficient explosive mixture to improve combustion and reduce pollutants.
The usual automotive vehicle using a gasoline powered internal combustion engine includes a fuel tank, a fuel pump and a carburetor. The carburetor is provided with a chamber for receiving gasoline from the fuel pump, and a float controlled valve maintains the gasoline at a constant level in the chamber. The usual carburetor includes a venturi through which air for combustion is drawn at substantial velocity, thus producing in the venturi a pressure substantially less than atmospheric. This reduced pressure induces a flow of fuel from the float chamber of carburetor, and as the gasoline in liquid phase emerges from jets or nozzles within the venturi, it is atomized or vaporized, or both, and mixed with the combiustion air flowing through the venturi.
The mixture of air and fuel is delivered to a manifold, and from the manifold is drawn into the engine's cylinders during the suction strokes of the pistons. The air/fuel mixture is compressed in each cylinder during the compression stroke of the piston, and is then ignited, either by a spark in the conventional engine, or by compression with or without supplementary heating means in a diesel engine. Ideally, combustion of the air/fuel mixture porgresses rapidly and is fully complete at the end of the power stroke of the piston. Too rapid burning or detonation is wasteful and causes knocking. Too slow burning results in some fuel failing to burn and being discharged in the exhaust. It is recognized that in the usual gasoline engine a very substantial percentage of fuel is wasted, and a relatively small percentage of the total energy available in the fuel is converted into usable energy by the engine.
Due to the inefficiencies of prior engines, many attempts have been made to improve the same by increasing the efficiency of the associated carburetion system. The ultimate purpose in increasing the efficiency of the carburetion system for an engine is to increase the percentage of fuel burnt in the cylinders, thereby increasing fuel economy and reducing certain undesirable combustion by-products such as hydrocarbons and carbon monoxide, and increasing other more desirable combustion by-products such as carbon dioxide.
It is generally accepted that reduction of harmful emissions could be accomplished by delivering a homogeneous mixture of air and fuel to the engine, thereby allowing lean mixtures to be burned with complete combustion. Many newer engines utilize fuel injectors rather than standard carburetor air/fuel mixing techniques to attempt to provide such homogeneous, lean air/fuel mixtures to the engine.
In a contnuous injection system, for example, air is drawn in the usual manner through the manifold and into the engine cylinders during the suction strokes of the pistons. Fuel injectors extend into the manifold or an air passageway immediately adjacent the cylinder intake port, for mixing fuel with the air immediately prior to entering the combustion chamber. In a mechanical system, the fuel injectors open at a pre-determined pressure, and after the engine is started, they remain open and continuously spray fuel. A vibrator pin inside the injector helps to break up and atomize the fuel droplets sprayed, and after the engine is stopped, the pin and a spring assembly seal off the injector to retain fuel pressure in the lines. This retention of pressure ensures quick starting.
Fuel metering is dependent on the volume of intake air into the engine. A mixture control unit measures incoming air flow and then distributes the correct amount of fuel to the cylinders to maintain a proper air/fuel ratio. In theory, constant maintenance of the air/fuel ratio results in improved performance, fuel economy and lowered exhaust emissions. In spite of the advance represented by fuel injection systems generally, it has been found that engine efficiency and fuel economy are still significantly less than ideal, and pollutant levels are correspondingly higher than that desired.
Accordingly, there is a need for an improved fuel injected internal combustion engine pollutant control system which allows leaner air/fuel mixtures to be efficiently burned within the engine cylinders without adversely affecting engine performance. Additionally, there is a need for a novel apparatus capable of safely and efficiently heating and partially vaporizing fuel into a specific mixture for injection into the intake airstream, and associated apparatus for heating the intake air prior to its combining with the heated injected fuel to form an explosive mixture. Moreover, there is a need for a system capable of conditioning the air prior to mixing with the fuel which, in addition to increasing engine efficiency, specifically lowers the temperature of combustion to decrease oxides of nitrogen as combustion by-products. Such systems and apparatus should be of simplified construction, maximize use of existing engine components, and be constructed of components known to be able to withstand the rigors of long-term automobile engine usage. The present invention fulfills these needs and provides other related advantages.